Nylon fibers are widely used in such diverse applications as carpets, ropes, parachutes, and tires. However, for some applications, including electrical insulation and fabric for protective clothing, there is a desire for nylon fibers exhibiting increased heat resistance, increased flame resistance, reduced moisture absorption, or some combination of these properties.
It was previously reported that the incompatibility of polyphenylene ether and polyamide led to difficulties in producing fibers. For example, U.S. Pat. Nos. 5,225,270 and 5,334,444 to Bhoori et al., and U.S. Pat. No. 5,559,194 to Kotek et al. disclose compositions that attempt to address this problem by requiring the addition of a third polymer component into the blend in order to produce polyphenylene ether/polyamide fibers. Specifically, U.S. Pat. Nos. 5,225,270 and 5,334,444 to Bhoori et al. require the addition of a functionalized olefinic elastomer, defined as having an ASTM D638 tensile modulus of less than about 40,000 pounds per square inch (276 megapascals). U.S. Pat. No. 5,225,270 to Bhoori et al., column 6, lines 15-19; U.S. Pat. No. 5,334,444 to Bhoori et al., column 7, lines 5-17. Useful functionalized olefinic elastomers include block and graft elastomers of one or more of ethylene, propylene, butylene, isopropylene, and isobutylene. U.S. Pat. No. 5,225,270 to Bhoori et al., column 6, lines 20-23; U.S. Pat. No. 5,334,444 to Bhoori et al., column 7, lines 18-21. And U.S. Pat. No. 5,559,194 to Kotek et al. requires the addition of a miscible amorphous polymer selected from polyamides prepared from terephthalic acid and 2,2,4-trimethylhexamethylene-diamine, polyamides prepared from terephthalic acid and 2,4,4-trimethylhexamethylenediamine, and polyamides prepared from hexamethylenediamine, isophthalic acid, and terephthalic acid. U.S. Pat. No. 5,559,194 to Kotek et al., column 2, lines 30-34.
There is a desire for simpler polyamide-polyphenylene ether compositions suitable for fiber spinning.